ISLAMABAD, Pakistan - The capture of the Afghan Taliban's No. 2 commander by a joint CIA and Pakistani team dealt a fresh blow to insurgents under heavy U.S. attack and raised hopes that Pakistani security forces are ready to deny Afghan militant leaders a safe haven.

Mullah Abdul Ghani Baradar's arrest in the Pakistani port city of Karachi may also push other insurgent leaders thought to be sheltering on this side of the border toward talks with the Afghan government - a development increasingly seen as key to ending the eight-year war.

Baradar, in his late 40s, was the second in command behind Taliban founder Mullah Mohammad Omar and was said to be in charge of the day-to-day running of the organization's leadership council, which is believed based in Pakistan. He was a founding member of the Taliban and is the most important figure of the hardline Islamist movement to be arrested in the war.

Baradar, who also functioned as the link between Mullah Omar and field commanders, has been in detention for more than 10 days and was talking to interrogators, two Pakistani intelligence officials said Tuesday. One said several other suspects were also captured in the raid. He said Baradar had provided "useful information" to them and that Pakistan had shared it with their U.S. counterparts. They spoke on condition of anonymity because of the sensitivity of the information.

The White House declined to confirm Baradar's capture. Spokesman Robert Gibbs told reporters the fight against extremists involves sensitive intelligence matters and he believes it's best to collect that information without talking about it.

President Barack Obama's administration has vowed to kill or seize Taliban and al-Qaida leaders in Afghanistan and Pakistan. The arrest comes as relentless CIA missile strikes against militant targets in the border tribal region have killed several commanders.

Obama has ordered 30,000 extra troops to southern Afghanistan. On Saturday, thousands of them began a major attack on the town of Marjah in the southern province of Helmand, one of the regions that Baradar is believed to control.

Former members of the Taliban regime in Afghanistan and security experts said the arrest would hurt the Taliban but was far from a decisive blow. They said Baradar would likely be quickly replaced and that local commanders had a lot of autonomy from the leaders based in Pakistan.

Nevertheless, the capture is likely to cause short-term disruption, since Baradar was the day-to-day commander of the Taliban and his successor would not have the same prestige.

"It's a great tactical success that the coalition forces should be pleased with, but by no means is it the beginning of the end," said Will Hartley, an analyst at Jane's Terrorism and Insurgency Center in London. "This will have a noted effect on the short-term ability of the Taliban to operate the way it was. However, it has proved itself a resilient organization."

Pentagon spokesman Col. Dave Lapan said he could neither confirm nor deny that Baradar was captured but said the removal of any senior leader would have "an immediate impact to their operations.'

"But we've seen, too, that they then push successors into their place... How long it takes them to sort of reconstitute depends on the situation."

Afghan analysts in the U.S. said they were closely watching for a stepped-up U.S. effort to capture or kill Jalaluddin Haqqani and his son Sirajuddin, the brutal leaders of the Taliban arm that operates in eastern Afghanistan from bases in northwestern Pakistan.

Pakistan helped create the Taliban and supported the militants' regime in Afghanistan before the Sept. 11, 2001, attacks on the United States, when threats from Washington forced Islamabad to disavow the group.

But Pakistan's spy agencies have long been accused of protecting top Afghan Taliban leaders - many of whom are believed to have fled to Pakistan during the U.S.-led invasion - to use them as tools to counter Indian influence in Afghanistan when the Americans withdraw.

With mounting U.S. casualties in across the border, American officials have pressured Pakistan to target the group's leaders. Security forces here have largely resisted doing so, even while attacking Pakistani Taliban groups blamed for scores of terror attacks.

U.S. and Pakistani officials did not say what led them to Baradar or give details of the raid, triggering speculation that he may have been handed over by Pakistani intelligence officials as part of a trade off in negotiations over the future of Afghanistan or betrayed by other members of the Taliban.

"If Pakistani officials had wanted to arrest him, they could have done it at any time," said Sher Mohammad Akhud Zada, the former governor of Afghanistan's Helmand province and a member of the Afghan parliament. "Why did they arrest him now?"

The arrest could mark a shift in strategy by Pakistan's powerful Inter Services Intelligence agency from protecting or turning a blind eye to the Afghan Taliban to arresting them.

"The Pakistani government have realized that the Taliban is too much of a threat to them, they've decided they've got to draw some red lines for both Pakistani and Afghanistan Taliban," said Michael Clarke, director of the Royal United Services Institute, a military think-tank in London. "They decided they need to be seen to take the Taliban on, they need to push them back."

Washington will be hoping that is true.

"It's really evidence of a stronger co-operative effort that's taking place," Sen. John Kerry, chairman of the Senate Foreign Relations Committee, told CBS' "The Early Show" from Islamabad, where he was on an unrelated visit when news of the capture broke.

Others cautioned it was too soon to say whether the arrest represented a strategic change or was a one-off event aimed at reducing some of the U.S. pressure on the country. Some said they believed it was simply the result of good intelligence work by the United States.

"I think the intelligence comes from the Americans," said Rahimullah Yousafzai, a Pakistani journalist and expert on the Taliban. "They tell the Pakistanis that 'we have to raid some place' and the Pakistanis say 'we will go along with you."'

The arrest strengthens reports that Karachi is increasingly being used by members of the Afghan Taliban as a base, possibly because their earlier havens close to the border are now the target of about three CIA missile attacks each week.

A chaotic city of 13 million people, Karachi has a large population of Pashtuns, the ethnic group that makes up the Taliban, meaning it is relatively easy for insurgents to hide there.

Taliban expert Michael Semple said Baradar was known as a "pragmatist" who could be prepared to enter into some kind of talks with the United States.

"If he could get guarantees, he would be willing to negotiate," said Semple, who was expelled from Afghanistan in 2007 by President Hamid Karzai for negotiating with midlevel Taliban commanders when he worked for the European Union.

Semple said the arrest could lead to more pressure on Afghan Taliban commanders to negotiate with the Afghan government if they thought that Pakistan was no longer safe. "I think that this will make the other leaders more inclined to negotiate," he said.